Benign Metastasizing Leiomyoma and Lymphangioleiomyomatosis. Lung Diseases of Women

This chapter reviews two rare lung diseases in women, benign metastasizing leiomyoma (BML) and lymphangioleiomyomatosis (LAM), which are non-neoplastic diseases that behave in many ways like neoplastic disease. They can be aggressive and their primary clinical manifestation in the lung may in fact represent a metastatic process. Their etiologies remain incompletely understood. Medical therapies to date have been ineffective due to the lack of clinical trials. Pulmonary transplantation remains a viable option for these patients. Earlier recognition of these diseases will lead to a better understanding of their pathogenesis and the development of newer treatments. BML is an extremely rare disease of unknown etiology that primarily affects women. Typically, the women are in their reproductive years and status post-hysterectomy for uterine leiomyomas. Since Steiner first described the disease in 1939, there have been approximately 100 reported cases of BML. Case reports provide sporadic and incomplete information on the natural history of the disease and there are no diagnostic or standard treatment protocols. The disease is not benign despite the hypothesis that BML originates from uterine leiomyomas, a common neoplasm that has a prevalence of 3-20%. Benign uterine smooth muscle cells spread hematogenously to the lung, the heart, lymph nodes, omentum, peritoneum, pelvic cavity, breast, bone, mediastinum, and nervous system. Although BML is usually diagnosed after an incidental finding on chest imaging, patients can present with mild pulmonary symptoms such as dyspnea on exertion and cough. The multiple, non-calcified, benign, smooth muscle pulmonary nodules of BML can mimic a malignancy.